Pope Benedict XVI is to resign at the end of this month in an unexpected development, saying he is too old to continue at the age of 85.

He became Pope in 2005 following John Paul II's death.

Resignations from the papacy are not unknown, but this is the first in the modern era, which has been marked by pontiffs dying while in office.

At 78, the former Cardinal Joseph Ratzinger was one of the oldest new popes in history when elected.

The BBC's Alan Johnston in Rome says the news has come "out of the blue", and that there was no speculation whatsoever about the move in recent days.

At 78, one of the oldest new popes in history when elected in 2005

Born in Germany in 1927, joined Hitler Youth during WWII and was conscripted as an anti-aircraft gunner but deserted

As Cardinal Joseph Ratzinger spent 24 years in charge of Congregation for the Doctrine of the Faith - once known as the Holy Office of the Inquisition

A theological conservative, with uncompromising views on homosexuality and women priests

He took the helm as one of the fiercest storms the Catholic Church has faced in decades - the scandal of child sex abuse by priests - was breaking.

The Vatican says it expects the period between the Pope's resignation and the election of his successor to be as brief as possible, but there has been no confirmation on when cardinals will meet to choose a new pontiff.

In a statement, the pontiff said: "After having repeatedly examined my conscience before God, I have come to the certainty that my strengths, due to an advanced age, are no longer suited to an adequate exercise of the Petrine ministry.

"I am well aware that this ministry, due to its essential spiritual nature, must be carried out not only with words and deeds, but no less with prayer and suffering.

"However, in today's world, subject to so many rapid changes and shaken by questions of deep relevance for the life of faith, in order to govern the bark of Saint Peter and proclaim the Gospel, both strength of mind and body are necessary, strength which in the last few months, has deteriorated in me to the extent that I have had to recognise my incapacity to adequately fulfil the ministry entrusted to me.

"For this reason, and well aware of the seriousness of this act, with full freedom I declare that I renounce the ministry of Bishop of Rome, Successor of Saint Peter, entrusted to me by the Cardinals on 19 April 2005, in such a way, that as from 28 February 2013, at 20:00 hours, the See of Rome, the See of Saint Peter, will be vacant and a Conclave to elect the new Supreme Pontiff will have to be convoked by those whose competence it is."

"I don’t wish any ill on any fellow primate or mammal of mine, so I don’t at all look forward to the death of Joseph Ratzinger, I don’t, or any other bloke, not really, except for one tiny reason which I ought to confess and share with you. When he dies, there’s quite a long interval till the conclave can meet, and for that whole time, that whole interval—it is a delicious, lucid interlude—there isn’t anyone on Earth who claims to be infallible. Isn’t that nice? All I think, all I want to propose in closing is this: that if the human species is to rise to the full height that’s demanded by its dignity, and by its intelligence, we must all of us move to a state of affairs, where that condition is permanent, and I think we should get on with it." - Christopher Hitchens. Well Christopher, he didn't even have to die.

Despite what people may think about the Catholic Church, Pope Benedict did quite a good job of leading them through quite a tumultuous time. Props to him for recognising that he is just too damn old to lead the Church in the modern era.

Celestine V's way of resignment seems somewhat similar to this: overwhelmed in office due to a history of bad choices. The child abuse claims/butler cover up pretty much ruined his tenure halfway through, so I'm not very surprised. As much as they'll cite press the reason being old age, the constant scandals seems like the obvious explanation.

I think its apalling that, when he manages to admit to his fallibility despite being of a position where delusions of grandeur are practically handed to people on a silver-platter, he is going to be met with a reminder of why people want him gone instead of being acknowledged as wanting to put the planetary spiritual crisis first.

Not to say Christianity is the soloution to that but what-ever happened to not saying bad things about people when they put themselves down.